Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new behavioral context: "Free." (cost/credit implications, relevant given siblings like estimate_cost and get_credit_balance) and the fact that interfaces may be frozen during parallel generation. It says nothing about failure modes when a subsystem is absent, payload size, or permissions.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

A single dense sentence, front-loaded with the cost signal and then a parallel list of payload items. Given there is no output schema, the enumeration earns its length, though the colon-and-comma list is slightly hard to parse at a glance.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description carries the burden of explaining what comes back and does so thoroughly, item by item. Missing are error behavior for unknown subsystem ids and any note on result size or whether ref defaults are inherited, which keeps it from a 5.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so model_id, subsystem_id and ref are already documented with patterns and examples. The description only tangentially adds meaning by mentioning the baseline id to generate against, which hints at the ref parameter's role. Baseline 3 applies when the schema does the heavy lifting.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description names the exact resource and enumerates its contents: boundary contracts with ports/items/units/rates, frozen interfaces, allocated functions, requirements, current text, and baseline id. That is far more specific than the name alone. It stops short of naming a sibling to distinguish from (e.g., mbe_list_subsystems or mbe_diff), so it is clear but not sibling-differentiated.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

"Everything an agent needs before generating a subsystem" gives an explicit trigger condition tied to the generation workflow, which is a real when-to-use signal. There is no explicit when-not or named alternative, so it falls short of a 5.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.